Items for auction will include universal plant (5)
I believe the answer is:
lotus
'plant' is the definition.
(lotus is a kind of plant)
'items for auction will include universal' is the wordplay.
'items for auction' becomes 'lots' (I've seen this before).
'will include' indicates putting letters inside.
'universal' becomes 'u'.
'lots' enclosing 'u' is 'LOTUS'.
(Other definitions for lotus that I've seen before include "Tropical water-lily" , "Plant that mythically induces languor" , "It helps with memory loss" , "Indian waterlily" , "Large water lily" .)